Abstract:
The damage caused by insects to cereal and legume stocks has been the subject of
numerous studies in Africa. The main aim of this work is to find natural substances
with an insecticidal effect against the bean pest Bruchus rufimanus, using extracts
from the leaves of the Ruta graveolens plant (Rutaceae) from the Zelfana - Ghardaïa
region as an alternative to synthetic pesticides that pollute the environment. The plant
leaves were extracted by maceration with two solvents: ethyl acetate and ethanol.
Qualitative analysis using phytochemical screening determined the presence of
several chemical compounds, in particular flavonoids, tannins, steroids and alkaloids.
The study of the insecticidal activity of R. graveolens extracts showed a very strong
toxic effect on Bruchus rufimanus adults with contact treatment, particularly for the
ethyl acetate extract. This efficacy is represented by calculated toxicological
parameters, namely LD 50 , LD 90 , TL 50 and TL 90 . The sensitivity of adults was variable
and even higher with increasing extract concentrations and exposure time.
Fractionation of ethyl acetate extract using chromatographic methods (column and
thin layer chromatography) yielded six fractions, which confirmed the toxicity of the
various compounds in the leaves of this plant. The bioactive substances contained in
the R. graveolens extract fractions were identified using high-performance liquid
chromatography (HPLC) which allows to detect the presence of: Chlorogenic acid,
Tannic acid, Quercetin, Adonitol, Gallic acid, Coumaric acid, Caffeic acid, Ascorbic
acid. In the context of biological control, the application of this insecticidal product
could be very effective against pests and for the protection of legume stocks.
